U.S. patent number 6,096,132 [Application Number 09/112,270] was granted by the patent office on 2000-08-01 for automatic painting device.
This patent grant is currently assigned to L.A.C. Corporation. Invention is credited to Tadashi Kaiba, Syusei Murai.
United States Patent |
6,096,132 |
Kaiba , et al. |
August 1, 2000 |
Automatic painting device
Abstract
An automatic painting device wherein control for driving spray
gun heads in a Z axis direction is executed correctly with respect
to a surface to be painted having a curved shape so that painting
can be effected while keeping a constant interval between the
plurality of spray gun heads and the surface to be painted. The
automatic painting device can include a spray gun head unit holding
a plurality of spray gun heads, an X axis direction driving
mechanism for driving the spray gun head unit in a horizontal X
axis direction, and a Y axis direction driving mechanism for
driving the spray gun head unit in a Y axis direction perpendicular
thereto, and in which different paints are ejected by the plurality
of spray gun heads. The different spray gun heads are held by the
spray gun head unit movably in a Z axis direction perpendicular to
the x axis direction and the Y axis direction, independently from
each other. The automatic painting device includes Z axis direction
driving motors, which drive the spray gun heads in the Z axis
direction, independently from each other on the basis of measured
data and set data relating to a distance between a relevant spray
gun head and an object to be painted. In this way the distance
between the different spray gun heads and the surface to be painted
constant can be kept constant, which improves remarkably the image
quality of painting.
Inventors: |
Kaiba; Tadashi (Tokyo,
JP), Murai; Syusei (Tokyo, JP) |
Assignee: |
L.A.C. Corporation (Tokyo,
JP)
|
Family
ID: |
27179207 |
Appl.
No.: |
09/112,270 |
Filed: |
July 8, 1998 |
Current U.S.
Class: |
118/680; 118/629;
118/679; 118/712 |
Current CPC
Class: |
B05B
13/0452 (20130101); B05B 12/00 (20130101); B41J
3/407 (20130101); B41J 11/001 (20130101); B41J
2/01 (20130101); B05B 12/1472 (20130101) |
Current International
Class: |
B41J
2/01 (20060101); B41J 3/407 (20060101); B05B
13/02 (20060101); B05B 13/04 (20060101); B41J
11/00 (20060101); B05C 011/00 () |
Field of
Search: |
;118/712,671,323,679,676,684,680,668,681,713,621,629 ;901/46 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
0 317 219 |
|
May 1989 |
|
EP |
|
0 333 609 |
|
Sep 1989 |
|
EP |
|
42 09 279 |
|
Sep 1993 |
|
DE |
|
Other References
Patent Abstracts of Japan; JP 09-206641, dated Aug. 12, 1997
English Language Abstract (1 page). .
Patent Abstracts of Japan; JP 08-057373, dated Mar. 5, 1996 English
Language Abstract (1 page). .
Patent Abstracts of Japan; JP 07-265755, dated Oct. 17, 1995
English Language Abstract (1 page)..
|
Primary Examiner: Crispino; Richard
Assistant Examiner: Koch, III; George R
Attorney, Agent or Firm: Flynn, Thiel, Boutell & Tanis,
P.C.
Claims
What is claimed is:
1. An automatic painting device comprising:
holding means for holding a plurality of air pressure ejection type
color ink spray gun heads movable in X, Y and Z axis
directions;
X and Y axis direction driving means for driving said holding means
in the X and Y axis directions parallel to a surface to be
painted;
Z axis direction driving means for driving said spray gun heads
independently from each other in the Z axis direction perpendicular
to the surface;
control means, which controls driving of said spray gun heads and
amounts of color paints ejected, depending on a position and a
color tone of each pixel of an original image;
measuring means for measuring displacement distances in the Z axis
direction from said spray gun heads to a plurality of coordinate
points in a desired region on the surface to be painted to output
measured data;
setting means for setting desired painting speeds and desired
painting distances in the Z axis direction from the surface to be
painted to output set data; and
input means for inputting the measured data and the set data to
said control means,
said control means comparing the measured data coming from said
measuring means with Z axis direction driving capacity data and,
when the control means judges from the comparison that said spray
gun heads can be driven safely, controlling driving of said spray
gun heads in the Z axis direction on the basis of the measured data
and the set data.
2. An automatic painting device according to claim 1, wherein said
measuring means includes a body measuring instrument, which
measures said Z axis direction displacement distances from said
spray gun heads to a coordinate point by bringing a marker into
contact with said coordinate point, and a measuring plate having a
shape analogous to said spray gun heads being mounted on an
extremity of said marker.
3. An automatic painting device according to claim 1, wherein said
measuring means includes a display for displaying the displacement
distance in the Z axis direction and sets an interval between
coordinate points in the X axis direction, depending on said
painting speeds and distances, over which said spray gun heads are
movable in the Z axis direction, corresponding to said coordinate
points, to effect measurements for obtaining data on said
coordinate points.
4. An automatic painting device according to claim 1, wherein said
measuring means for measuring the displacement distance from said
spray gun heads to the surface to be painted is mounted to said
holding means adjacent said spray gun heads.
5. An automatic painting device according to claim 1, wherein said
Z axis direction driving means comprises an individual drive motor
for each respective said spray gun head, each of said individual
drive motors capable of moving the respective said spray gun head
independently from adjacent spray gun heads.
6. An automatic painting device according to claim 1, wherein said
spray gun heads are aligned in a row on said holding means, each of
said spray gun heads ejecting a different color of the paint.
7. An automatic painting device according to claim 1, wherein a
stationary frame member supports said X and Y axis direction
driving means and said holding means.
8. An automatic painting device comprising:
support means for supporting a plurality of air pressure ejection
type spray gun heads movable in X and Y directions;
X and Y axis direction driving means for driving said support means
in the X and Y axis directions, the X and Y axis directions
defining a plane substantially parallel to a surface to be
painted;
Z axis direction driving means for driving said spray gun heads
independently from each other in the Z axis direction perpendicular
to the surface to be painted;
control means for controlling the driving means and amounts of
paint applied;
measuring means for measuring displacement distances in the Z axis
direction from said spray gun heads to a plurality of coordinate
points on the surface to be painted and for outputting measured
data; and
setting means for setting desired painting speeds and painting
distances in the Z axis direction from the surface to be painted as
output set data,
wherein said control means compares the measured data with Z axis
direction driving capacity data to ensure safe driving of said
spray gun heads in the Z axis direction and, if safe operation is
indicated, controlling driving of said spray gun heads in the Z
axis direction on the basis of the measured data and the set
data.
9. An automatic painting device according to claim 8, wherein said
spray gun heads are aligned in a row on said support means, each of
said spray gun heads ejecting a different color paint in a selected
amount to form a color tone.
10. An automatic painting device according to claim 8, wherein said
Z axis direction driving means comprises an individual drive motor
for each respective said spray gun head.
11. An automatic painting device according to claim 8, wherein said
measuring means for measuring the displacement distance from said
spray gun heads to the surface to be painted is mounted to said
support means adjacent said spray gun heads.
12. An automatic painting device according to claim 8, wherein each
of said plurality of spray gun heads includes a different color
paint.
13. An automatic painting device comprising:
a spray gun head unit supporting a plurality of air pressure
ejection type spray gun heads;
X and Y axis direction driving means for driving said spray gun
head unit in the X and Y axis directions, the X and Y axis
directions defining a plane substantially parallel to a surface to
be painted;
a plurality of Z axis direction driving motors mounted on said
spray gun head unit and corresponding to each of said spray gun
heads for driving said spray gun heads independently from each
other in the z axis direction substantially perpendicular to the
surface to be painted;
control means for controlling the driving means and amounts of
paint applied by said spray gun heads depending on a position and a
color tone of each pixel of an original image;
measuring means supported on said spray gun head unit for measuring
displacement distances in the Z axis direction from said spray gun
heads to the surface to be painted for a plurality of coordinate
points and outputting measured data; and
setting means for setting desired painting speeds and painting
distances in the Z axis direction from the surface to be painted as
output set data,
wherein said control means compares the measured data with Z axis
direction driving capacity data to ensure safe driving of said
spray gun heads in the Z axis direction and, if safe operation is
indicated, controlling driving of said spray gun heads in the Z
axis direction on the basis of the measured data and the set
data.
14. An automatic painting device according to claim 13, wherein
said spray gun heads are aligned in a row on said spray gun head
unit, each of said spray gun heads ejecting a different color
paint.
15. An automatic painting device according to claim 13, wherein
said support means comprises a stationary frame member supporting
said X and Y axis direction driving means and said spray gun head
unit.
16. An automatic painting device according to claim 13, wherein
said measuring means includes a display for displaying the
displacement distances in the Z axis direction.
Description
FIELD OF THE INVENTION
The present invention relates to an automatic painting device
capable of painting a desired colored image on a surface to be
painted by driving three-dimensionally a plurality of air pressure
ejection type color ink spray gun heads and in particular to an
improvement for making clear painting possible with precise color
tone, even if the surface to be painted is a complicated curved
shape such as a body of an automobile.
DESCRIPTION OF THE PRIOR ART
Recently a printer of ink jet type has been used as a printing
device for a computer. This ink jet printer reproduces color tone
for pixels by ejecting inks of four colors, which are the three
primary colors of red, blue and yellow, and black from each of
nozzles, superposing them on a print, and responding to the color
tone of each of the pixels stored in a memory device in a computer.
Then it is possible to paint image data on a print sheet of paper
by driving the nozzles in right and left directions and the print
sheet in a perpendicular direction.
In a printer, material to be painted is restricted to a paper-like
matter. If it is possible to paint image data by an ink spray gun
head system directly, e.g. on a body of an automobile, etc., even
complicated designs can be reproduced industrially by mass
production.
FIGS. 12 to 14 show an example of a prior art automatic painting
device.
In FIG. 12, reference numeral 1 is a CPU for processing image data;
2 is a mechanism for controlling drive of the spray gun heads and
ejected amounts of color inks; 3 is a CPU for controlling the
mechanism; 4 is a memory; 5 is a key board for manually operating
the mechanism; 6 is an LCD display device displaying operation by
means of the key board; 7, 8, 9 and 10 are an NTSC input terminal,
an image scanner input terminal, a mouse input terminal and a first
floppy disk input terminal, respectively.
Further, 11 is an A/D converter; 12 is a memory; 13 and 14 are
input/output sections; 15 is a frame memory; 16 is a D/A converter;
17 is a monitor output terminal; and 18 is a second floppy disk
output terminal.
Still further the mechanism 2 consists of an X and a Y axis driving
mechanism 20 and 21 for driving spray gun heads in an X and a Y
axis direction with respect to a wall surface and a Z axis driving
mechanism 22 for controlling a distance from the wall surface so as
to keep it at a predetermined value as well as color ink ejection
amount controlling mechanisms 23 for the spray gun heads, etc.
This ink jet printer is so constructed that output signals from a
video deck VD, a video camera VM, an image scanner IM, a serial
mouse SM and a first floppy disk FD.sub.1 are inputted to the input
terminals 7 to 10, respectively, and that these output signals,
i.e. image data, are input to the CPU 1 to be subjected thereby to
image processing such as addition, etc. of the image data so that
signals necessary for painting are given to the other CPU 3 for
controlling the mechanism through the input/output section 14.
Further the CPU 1 for image processing stores painting signals
obtained by editing the image data taken-in from the different
input terminals in a second floppy disk FD.sub.2 through the output
terminal 18 so that they can be utilized if necessary. The painting
signals are output to the output terminal 17 through the frame
memory 15 and the D/A converter 16 so that they can be monitored by
a color monitor CM.
The different mechanisms for driving the spray gun heads are
disposed on a frame 30 as indicated in FIG. 15.
The frame 30 consists of upper, low, left and right frame units 31
to 34 as well as left and right leg members 35 and 36 assembled
together by means of screws, as indicated in FIG. 16, and is fixed
parallelly to a wall surface 37 with a predetermined distance at a
job site, as indicated in FIG. 17.
The X and the Y axis driving mechanisms 20 and 21 are disposed so
as to be opposite to the frame 30, as indicated in FIG. 18.
The X axis driving mechanism 20 consists e.g. of a fixed portion 40
mounted on the frame 30 and a driving portion 40 moving along the
fixed portion 40 as indicated in FIG. 19. The fixed portion 40
comprises a rail 42 and a rack gear 43 and on the other hand the
driving portion 41 is provided with a linear roller 44, a pignon
gear 45, a reduction gear 46, a motor 47, a rotary encoder 48 and a
Z axis driving mechanism supporter 49. The linear roller 44 is
engaged with the rail 42 slidably along it and the pignon gear 45
is in gear with the rack gear 43.
Responding to an X axis control signal from the CPU 3, the motor 47
drives the pignon gear 45 through the reduction gear 46 and in this
way it can move the Z axis driving mechanism supporter 49 in the X
axis direction along the rail 42 by a predetermined distance at a
time.
As indicated in FIG. 18, the Y axis driving mechanism 21 consists
of Y axis driving units 21a and 21b, each of which has an
approximately same construction as the X axis driving mechanism.
These units are disposed on the left and right frame units 33 and
34 of the frame 30 to support the two extremities of the X axis
driving mechanism 20. In this way, responding to a Y axis control
signal from the CPU 3, it can move the X axis driving mechanism 20
in a Y axis direction (up- and downward).
As indicated in FIG. 23, the Z axis driving mechanism 22 consists
e.g. of a movable controller 221, a photo sensor 222, a four-spray
gun-head unit 223, a spray gun head supporting plate 224, etc.
disposed on the supporter 49 of the X axis driving mechanism 20.
The movable controller 221 comprises a roller 225 and a linear
pulse motor 226 for position control in a Z axis direction and
responding to a signal from the photo sensor 222 mounted on an
extremity lower portion of the supporting plate 224, it controls
the spray gun head unit 223 according to instruction pulses from
the CPU 3 so that the distance L of the spray gun heads 223a to
223d from a wall surface 227 is kept constant.
In the automatic painting device, when image signals corresponding
to an original image to be printed are inputted to either one of
the input terminals 7 to 10, they are sent to the CPU 1 to be
processed thereby so
that signals necessary for a print are given to the CPU 3 for
controlling the mechanism. Responding to the signals, the CPU 3
sends driving control signals to the different mechanisms 20, 21,
22 and 23 to drive the spray gun head unit 223 in the X and the Y
axis direction while keeping the distance thereof from the wall
surface constant and to eject inks from the spray gun heads for
each pixel of the image in order to print an enlarged color image
and move the different mechanisms to following pixels
successively.
Concerning movement in the Z axis direction, the distance from the
wall surface to be painted is detected by the photo sensor 222. By
signals thus detected the linear pulse motor is driven to move the
supporter 49 and the spray gun heads 223a to 223d are controlled so
that the distance thereof from the wall surface is kept constant.
By using this automatic painting device, since it is possible to
paint the image data in an enlarged scale on the wall surface to be
painted by driving the spray gun head units 223 in the X axis and
the Y axis direction and to keep the distance of the spray gun
heads from the wall surface constant by driving the supporter 49 in
the Z axis direction, even if the wall surface to be painted has a
curved shape, it is possible to obtain a clear print.
By the automatic painting device described above, a pixel having a
predetermined color tone can be printed by superposing inks ejected
by the four spray gun heads 223a to 223d at one point. However, in
cases where the wall surface to be painted has a complicated uneven
curved shape, positions of inks ejected by the four spray gun heads
are subtly shifted from each other. Therefore there was a fear that
the color tone at a point differed from that at other points or it
was unclear.
For example, in some cases the case positions where the four spray
gun heads 223a to 223d are mounted, are shifted slightly from each
other in the left and right direction as indicated in FIG. 20. If a
wall surface 600 to be painted has a shape including an inclined
part 601, distances of the spray gun heads 223a to 223d from the
wall surface to be painted differ from each other. That is, as
indicated in FIGS. 21 and 22, in a case where a point P is painted
by the spray gun head 223a located at the left extremity, the
distance between the wall surface 600 to be painted and the photo
sensor 222 is L. However, when the succeeding spray gun head 223b
paints the point P, the spray gun head unit 223 is shifted in the X
axis direction in order that the nozzle hole of the spray gun head
223b is placed at a position opposite to the point P. As the
result, the photo sensor 222 is opposite to an inclined part 601
and therefore the distance between the wall surface to be painted
600 and the photo sensor 222 is L' greater than L. Therefore the
supporter 49 is driven to be advanced in order to make the value
detected by the photo sensor 222 equal to that obtained for the
spray gun head 223a. As the result, the distance between the spray
gun head 223b and the wall surface to be painted 600 becomes
smaller, which varies the painted area, giving rise to
inconveniences that the color tone differs from that of surrounding
parts and that clarity lowers.
In order to remove the inconveniences, it is necessary that each of
the spray gun heads 223a to 223d is held movably in the Z axis
direction and that painting can be effected while driving the
different spray gun heads so that the distance (interval) in the Z
axis direction between the wall surface to be painted and them is
kept constant. For this reason, it is conceivable to adopt a
method, wherein a sensor detecting the displacement distance in the
Z axis direction is disposed on the spray gun head unit and drive
of the unit is controlled by using a detection signal of the
sensor.
However, in reality, this method cannot be applied in practice.
This is because the spray gun head unit is driven in the X and the
Y axis direction with a constant speed and in case where the wall
surface to be painted has a curved shape such as a body of an
automobile, if following control in the Z axis direction is
executed by using this detection signal of the sensor, since there
is a limit in response speed of this control, the following control
of the displacement in the Z axis direction cannot be effected
correctly. Further, in case where there is a difference in level in
the Z axis direction, etc., there is a fear that the spray gun
heads are damaged.
SUMMARY OF THE INVENTION
In order to solve such a problem, an object of the present
invention is to provide a device capable of painting automatically
a desired colored image directly on a surface to be painted having
a curved shape such as a body of an automobile, which makes it
possible to control displacement of spray gun heads in a Z axis
direction by following variations of the surface to be painted,
without using any displacement distance sensor in the Z axis
direction.
In order to achieve the above object, an automatic painting device
according to the present invention, comprising holding or
supporting means, which holds or supports a plurality of air
pressure ejection type color ink spray gun heads movably in X, Y
and Z axis directions; X and Y axis direction driving means, which
drive the holding means in the X and Y axis directions; Z axis
direction driving means, which drive the spray gun heads
independently from each other in the Z axis direction; control
means, which controls drive of the spray gun heads and ejected
amounts of color inks, depending on a position and a color tone of
each pixel of an original image, is characterized in that it
comprises further measuring means, which measures displacement
distances in the Z axis direction from the spray gun heads to a
plurality of coordinate points (Xi, Yi) in a desired region on a
surface to be painted to output measured data; setting means, which
sets desired painting speeds and desired painting distances in the
Z axis direction from the surface to be painted to output set data;
and input means, which compares the measured data coming from the
measuring means with Z axis direction driving capacity data and
inputs them together with the set data to the control means, when
it is judged that they can be driven, in order that the control
means controls drive of the spray gun heads on the basis of
the-data.
In the present invention, the measuring means may include a body
measuring instrument, which measures the Z axis direction
displacement distances from the spray gun heads to a coordinate
point by bringing a marker into contact with the coordinate point,
and a measuring plate having a shape analogous to the spray gun
heads may be mounted on an extremity of the marker.
Further, in the present invention, the measuring means may set an
interval between coordinate points in the X axis direction,
depending on the painting speeds and distances, over which the
spray gun heads can be moved in the Z axis direction, corresponding
to the coordinate points, to effect measurements for obtaining data
on the coordinate points.
An automatic painting device according to the present invention
comprises a plurality of, e.g. four, well-known air pressure
ejection type color ink spray gun heads of four colors; a unit
holding these spray gun heads movably in X, Y and Z axis
directions; X and Y axis direction driving means, which drives the
unit; Z axis direction driving means, which drives the spray gun
heads independently from each other in the Z axis direction;
control means comprising a computer, which controls drive of the
spray gun heads and ejected amounts of color inks, depending on the
position and the color tone of each pixel of an original image,
etc.
Well-known means can be adopted for the X, Y and Z axis direction
driving means, for drive by engagement of a rack with a pignon;
drive by a cylinder device, drive by using a stepping motor,
etc.
The device according to the present invention is characterized in
that data (Xi, Yi, Zi) of a plurality of coordinate points in a
desired region on a surface to be painted are measured without
using any Z axis direction displacement distance sensors and at the
same time desired painting speeds (print speeds) and desired
painting distances (print surface distances) in the Z axis
direction from the surface to be painted are set. Since the spray
gun heads are damaged, if the measured data are used as they are,
i.e. if measured data (large difference in level, etc.) exceeding
driving capacity in the Z axis direction are input and the spray
gun head unit is driven according thereto, the measured data are
compared previously with driving capacity data and used, only if it
is judged that the spray gun head unit can be driven according to
these data. At this time, the control means controls drive of the
spray gun heads on the basis of these measured data (body data) and
set data.
For example, data of coordinate points consist of data (Xi, Yi)
obtained by setting orthogonal coordinate points in the X and Y
axis directions and data (Zi) obtained by measuring Z axis
direction distances from these coordinate points. These data are
given previously to a computer serving as the control means.
In this case, since there can be differences in the Z axis
direction distance, over which the spray gun head unit can be
moved, when it is displaced transversally (X axis direction
displacement distance), at setting the coordinate points, it is
preferable that the interval in the X axis direction between
coordinate points is set, depending on the set painting speed and
the Z axis direction distance, over which the spray gun head unit
can be moved, to effect measurements of the data of the coordinate
points.
When the body data (Z axis direction displacement distance Zi)
measured as described above as well as the set painting speed and
distance from the surface to be painted are given to the computer,
at first control signals in the X and the Y axis direction
necessary for painting, based on the data (Xi, Yi) of the original
image, are transmitted to the X, Y axis direction driving means and
the spray gun head unit is moved to a predetermined position so
that one of the spray gun heads is placed at a position opposite to
a point on the surface to be painted. Then, since the Z axis
direction displacement distance to the point to be painted is given
as the measured data, the Z axis direction driving means is driven
so that it is at that distance and thereafter a predetermined
amount of color ink is ejected from the spray gun head so as to
have a concentration obtained on the basis of the image data, to
paint the image. This control process is effected for all the spray
gun heads and color inks from the different spray gun heads which
are superposed on each other at the point to be painted to paint it
with a predetermined color tone. The point on the surface to be
painted corresponding to each pixel in the original image is moved
one after another and the same control process is effected for all
the points to be painted to terminate the painting.
As described above, by using the automatic painting device, the Z
axis direction displacement distance between the surface to be
painted and the different spray gun heads is given previously by
the measured data and they are driven independently from each other
on the basis thereof. Consequently, even if the surface to be
painted has a curved shape such as a body of an automobile, it is
possible to keep easily the distance between each of the spray gun
heads and the surface to be painted constant. Since image quality
is remarkably improved and in addition the Z axis direction
displacement distance can be correctly controlled by using body
data previously measured and given without using any sensor, can be
completely prevented damage to the spray gun heads.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram for explaining a relation between spray gun
heads and a surface of a body to be painted;
FIG. 2 is a diagram for explaining a method for measuring body
data;
FIG. 3 is a perspective view showing a body data measuring
instrument;
FIG. 4 is another diagram for explaining the method for measuring
body data;
FIG. 5 is a diagram showing an example of a region to be painted of
a body of an automobile;
FIG. 6 is a diagram for explaining a method for determining points
to be measured;
FIG. 7 is a diagram showing a relation between a difference in
level in a Z axis direction and an interval between points to be
measured;
FIG. 8 is a diagram showing distances from the surface to be
painted;
FIG. 9 is a block diagram showing an embodiment of the present
invention;
FIG. 10 is a block diagram showing a principal part of the
embodiment;
FIG. 11 is a perspective view showing a spray gun head unit used in
a device according to the present invention;
FIG. 12 is a block diagram showing an example of a prior art
automatic painting device;
FIG. 13 is a perspective view showing a prior art CPU used in the
device indicated in FIG. 12;
FIG. 14 is a block diagram showing a principal part of the prior
art device indicated in FIG. 12;
FIG. 15 is a perspective view showing a prior art frame used in the
device indicated in FIG. 12;
FIG. 16 is an exploded perspective view of the prior art frame;
FIG. 17 is a side view of the frame;
FIG. 18 is a cross-sectional view of the prior art frame;
FIG. 19 is a perspective view showing an X and Y axis prior art
driving mechanism mounted on the frame;
FIG. 20 is a diagram showing an outline of the prior art spray gun
head unit;
FIG. 21 is a diagram showing a relation in an X axis direction
between the prior art spray gun head unit and a surface to be
painted; and
FIG. 22 is a diagram showing another relation in the X axis
direction between the prior art spray gun head unit and the surface
to be painted.
FIG. 23 is an illustration of an example of a prior art automatic
painting device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinbelow the present invention will be explained more concretely
by using an embodiment. Points where the present invention differs
from the prior art automatic painting device consist in the
construction of a Z axis direction drive control section
corresponding to the Z axis direction driving mechanism 23
described previously as well as the spray gun head unit and in that
an instrument for measuring a Z axis displacement distance is used.
Construction of the other major part such as the X and Y axis
direction driving mechanism, etc. is almost identical to those used
in the prior art automatic painting device.
In a case where e.g. a body 501 of an automobile is painted by
means of an automatic painting device having (four) spray gun heads
of four colors, as indicated in FIG. 1, it has been already
described that it is necessary to move a spray gun head unit 500 in
the X and the Y axis direction while keeping the distance in the Z
axis direction from a curved surface of the body always constant,
to print. X and Y axis direction driving signals for the spray gun
heads are obtained easily by processing original image data and on
the other hand Z axis direction driving signals are obtained by
calculation, starting from the measured data and the set data.
FIGS. 2 to 4 show an example of the method for measuring the Z axis
direction displacement distance (body data) in the present
invention. In FIG. 2, 502 is a frame member supporting the X, Y, Z
axis direction displacement mechanisms for the spray gun head unit
500 and 503 is a body measuring instrument for measuring the Z axis
direction displacement distance, which is mounted on the right side
surface of the spray gun head unit 500.
The body measuring instrument 503 has a bar-shaved marker 503b,
which is moved in the Z axis direction by rotating a knob 503a, as
indicated in FIG. 3. A measurement plate 503c is mounted at the
extremity thereof. The measurement plate 503c has a shape analogous
to that of the spray gun head unit 500.
When the marker 503b is moved by rotating the knob 503a to bring
the measuring plate 503c into contact therewith, as indicated in
FIG. 4, the Z axis direction displacement distance Z; is measured
and a measured value thereof is displayed on a display section
503d. At the same time it is transmitted to a Z axis direction
drive control section described later.
This process is repeated successively for a plurality of coordinate
points (Xi, Yi) e.g. on a surface to be painted of a body 501 of an
automobile.
As described above, at measuring the Z axis direction displacement
distance, by using the measurement plate 503c, at the same time as
the measurement of Zi, it is possible to judge beforehand the
possibility of the displacement or driving of the spray gun heads
in the Z axis direction with respect to the measurement points.
Coordinate points (measurement points) to be measured are
determined, depending on the shape of the body in a region to be
painted 505, as indicated in FIG. 5. The principle, according to
which the measurement points are determined, is as follows. For
example, as indicated in FIG. 6, (i) the two extremities 506 and
507 of the region to be painted 505 in the X axis direction are
forced measurement points, and (ii) positions 508 and 509, where
variations in the X and the Y axis direction are great, are forced
measurement points.
Further, particularly as indicated in FIG. 7, when a protrusion D
exists on the surface to be painted and a difference in level Z is
great, measurement points P.sub.1, P.sub.2 are selected so as to be
relatively far separated therefrom so that the displacement in the
Z axis direction is possible.
Further a desired distance Zo from the surface to be painted in the
Z axis direction is set together with a desired painting speed.
This is a distance in the Z axis direction between the extremity of
the spray gun head unit and the surface to be painted. A
displacement of Zi-Zo in the Z axis direction may be effected by
setting with which distance from the surface to be painted the
painting should be effected.
The control device used in the present embodiment comprises a
painting control section 510 corresponding to the X, Y axis
direction driving mechanism and a Z axis direction drive control
section 511 corresponding to the Z axis direction driving
mechanism, as indicated in FIG. 9. The painting control section 510
drives the different driving mechanisms and motors for driving them
according to shape data of the surface to be painted and mounting
position data of the spray gun heads 504. In this way the spray gun
head unit 500 is driven in the X and the Y axis direction so that
one of the spray gun heads 504 is located at a position opposite to
a certain point to be painted. Painting is effected by driving the
four spray gun heads 504 independently from each other so as to
eject paints or inks. Further the Z axis direction drive control
section 511 receives the measured data and the set data coming from
input means (body measuring instrument) 503 and controls stepping
motors driving the different spray gun heads, depending on the
distances from the surface to be painted, to determine positions in
the Z axis direction of the different spray gun heads 504.
FIG. 10 shows the construction of the Z axis direction drive
control section 511. At first, positions of one of the spray gun
heads 504 in the X and the Y axis direction are determined. This
determination may be effected manually or data previously stored in
a memory may be used therefor. The driving mechanisms and the
motors for driving them are driven on the basis of these position
data to determine the positions in the X and the Y axis direction
of the respective spray gun head 504. When the set value Zo and the
measured value Zi of the Z axis direction displacement distance is
inputted from the input means 503, a judging section 65 compares Zi
with the Z axis direction drive capacity data, and when it is
judged that the spray gun head unit can be driven, Zi is stored in
a data memory 61 together with Zo. The Z axis direction drive
capacity data is determined in order to prevent damage of the spray
gun heads during displacement thereof and set previously, depending
on the shape of the surface to be painted, etc. A CPU 60 compares
address values (position data) in the X and the Y axis directions
with the data stored in a data memory 61 and controls drivers 63
for the stepping motors in the X, the Y and the Z axis drive
directions through an I/O port 62 so that the set values and the
measured values coming from the input means 503 are approximately
equal to the data stored in the data memory 61 and that the spray
gun heads 504 are moved in the Z axis direction to determine the
position thereof. At that position color ink is ejected from one of
the spray gun heads 504 so that the point is painted in one of the
three primary colors or black. The point on the surface to be
painted is painted in a predetermined color tone by repeating this
control for the other three spray gun heads 504.
In case where CAD data, teaching data, etc. are used, these data
can be utilized if necessary by inputting previously these data to
a program memory 64. As described above, by using the automatic
painting device according to the present embodiment, since
displacements in the Z axis direction of the different spray gun
heads 504 are controlled independently from each other, it is
possible to control the spray gun heads 504 so that the distances
between the surface to be painted and them are kept constant, even
if the surface to be painted has a complicated curved shape and
therefore to paint clearly in a predetermined color tone.
FIG. 11 shows an example of the construction of the spray gun head
unit used in the device according to the present invention, in
which 101 to 104 are spray gun heads, which are supported movably
in the Z axis direction on a base plate 105 by driving motors 106
to 109, pignon gears 111 to 114, rack gears 115 to 118 and slide
rails 120 to 123. As described above, this unit itself is mounted
movably in addition in the X and the Y axis direction on the frame
member 502.
124 to 127 are nozzles for the different color inks of Y, M, C and
K. These nozzles may be disposed separately from the spray gun
heads, which are fed through flexible ink pipes. 128 to 131 are
inlets for taking-in air pressure fed through flexible hoses.
Further 132 to 135 are flexible signal cables for the different
spray gun heads.
It is preferable that the air hoses, the signal cables, etc. are
disposed, accommodated e.g. in a flexible cable caterpillar.
As explained above, by using an automatic painting device according
to the present invention, it is possible to paint clearly in a
predetermined color tone on a surface to be painted having a
complicated curved shape such as a body, a bumper of an automobile,
etc.
Although a particular preferred embodiment of the invention has
been disclosed in detail for illustrative purposes, it will be
recognized that variations or modifications of the disclosed
apparatus, including the rearrangement of parts, lie within the
scope of the present invitation.
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